A novel computational approach to integrate NMR spectroscopy and capillary electrophoresis for structure assignment of heparin and heparan sulfate oligosaccharides

Sulfate: a neglected (but potentially highly relevant) anion

Sulfate is an important anion as sulfonation is essential in modulation of several compounds, such as exogens, polysaccharide chains of proteoglycans, cholesterol or cholesterol derivatives and tyrosine residues of several proteins. Sulfonation requires the presence of both the sulfate donor 3'-phosphoadenosine-5'-phosphosulfate (PAPS) and a sulfotransferase. Genetic disorders affecting sulfonation, associated with skeletal abnormalities, impaired neurological development and endocrinopathies, demonstrate the importance of sulfate. Yet sulfate is not measured in clinical practice. This review addresses sulfate metabolism and consequences of sulfonation defects, how to measure sulfate and why we should measure sulfate more often.

Informatics Ecosystems to Advance the Biology of Glycans

Glycomics researchers have identified the need for integrated database systems for collecting glycomics information in a consistent format. The goal is to create a resource for knowledge discovery and dissemination to wider research communities. This has the potential and has exhibited initial success, to extend the research community to include biologists, clinicians, chemists, and computer scientists. This chapter discusses the technology and approach needed to create integrated data resources and informatics ecosystems to empower the broader community to leverage extant glycomics data. The focus is on glycosaminoglycan (GAGs) and proteoglycan research, but the approach can be generalized. The methods described span the development of glycomics standards from CarbBank to Glyco Connection Tables. Integrated data sets provide a foundation for novel methods of analysis such as machine learning and deep learning for knowledge discovery. The implications of predictive analysis are examined in relation to disease biomarker to expand the target audience of GAG and proteoglycan research.

Glycosaminoglycan Interactions with Chemokines Add Complexity to a Complex System

Chemokines have two types of interactions that function cooperatively to control cell migration. Chemokine receptors on migrating cells integrate signals initiated upon chemokine binding to promote cell movement. Interactions with glycosaminoglycans (GAGs) localize chemokines on and near cell surfaces and the extracellular matrix to provide direction to the cell movement. The matrix of interacting chemokine–receptor partners has been known for some time, precise signaling and trafficking properties of many chemokine–receptor pairs have been characterized, and recent structural information has revealed atomic level detail on chemokine–receptor recognition and activation. However, precise knowledge of the interactions of chemokines with GAGs has lagged far behind such that a single paradigm of GAG presentation on surfaces is generally applied to all chemokines. This review summarizes accumulating evidence which suggests that there is a great deal of diversity and specificity in these interactions, that GAG interactions help fine-tune the function of chemokines, and that GAGs have other roles in chemokine biology beyond localization and surface presentation. This suggests that chemokine–GAG interactions add complexity to the already complex functions of the receptors and ligands.

Glycomic and glycoproteomic analysis of glycoproteins-a tutorial

The structural analysis of glycoproteins is a challenging endeavor and is under steadily increasing demand, but only a very limited number of labs have the expertise required to accomplish this task. This tutorial is aimed at researchers from the fields of molecular biology and biochemistry that have discovered that glycoproteins are important in their biological research and are looking for the tools to elucidate their structure. It provides brief descriptions of the major and most common analytical techniques used in glycomics and glycoproteomics analysis, including explanations of the rationales for individual steps and references to published literature containing the experimental details necessary to carry out the analyses. Glycomics includes the comprehensive study of the structure and function of the glycans expressed in a given cell or organism along with identification of all the genes that encode glycoproteins and glycosyltransferases. Glycoproteomics which is subset of both glycomics and proteomics is the identification and characterization of proteins bearing carbohydrates as posttranslational modification. This tutorial is designed to ease entry into the glycomics and glycoproteomics field for those without prior carbohydrate analysis experience.

Glycomic and glycoproteomic analysis of glycoproteins-a tutorial

The structural analysis of glycoproteins is a challenging endeavor and is under steadily increasing demand, but only a very limited number of labs have the expertise required to accomplish this task. This tutorial is aimed at researchers from the fields of molecular biology and biochemistry that have discovered that glycoproteins are important in their biological research and are looking for the tools to elucidate their structure. It provides brief descriptions of the major and most common analytical techniques used in glycomics and glycoproteomics analysis, including explanations of the rationales for individual steps and references to published literature containing the experimental details necessary to carry out the analyses. Glycomics includes the comprehensive study of the structure and function of the glycans expressed in a given cell or organism along with identification of all the genes that encode glycoproteins and glycosyltransferases. Glycoproteomics which is subset of both glycomics and proteomics is the identification and characterization of proteins bearing carbohydrates as posttranslational modification. This tutorial is designed to ease entry into the glycomics and glycoproteomics field for those without prior carbohydrate analysis experience.

An integrated approach using orthogonal analytical techniques to characterize heparan sulfate structure

Heparan sulfate (HS), a glycosaminoglycan present on the surface of cells, has been postulated to have important roles in driving both normal and pathological physiologies. The chemical structure and sulfation pattern (domain structure) of HS is believed to determine its biological function, to vary across tissue types, and to be modified in the context of disease. Characterization of HS requires isolation and purification of cell surface HS as a complex mixture. This process may introduce additional chemical modification of the native residues. In this study, we describe an approach towards thorough characterization of bovine kidney heparan sulfate (BKHS) that utilizes a variety of orthogonal analytical techniques (e.g. NMR, IP-RPHPLC, LC-MS). These techniques are applied to characterize this mixture at various levels including composition, fragment level, and overall chain properties. The combination of these techniques in many instances provides orthogonal views into the fine structure of HS, and in other instances provides overlapping / confirmatory information from different perspectives. Specifically, this approach enables quantitative determination of natural and modified saccharide residues in the HS chains, and identifies unusual structures. Analysis of partially digested HS chains allows for a better understanding of the domain structures within this mixture, and yields specific insights into the non-reducing end and reducing end structures of the chains. This approach outlines a useful framework that can be applied to elucidate HS structure and thereby provides means to advance understanding of its biological role and potential involvement in disease progression. In addition, the techniques described here can be applied to characterization of heparin from different sources.

Informatics tools to advance the biology of glycosaminoglycans and proteoglycans

Glycomics researchers have identified the need for integrated database systems for collecting glycomics information in a consistent format. The goal is to create a resource for knowledge discovery and dissemination to wider research communities. This has the potential to extend the research community to include biologists, clinicians, chemists, and computer scientists. This chapter discusses the technology and approach needed to create integrated data resources to empower the broader community to leverage extant glycomics data. The focus is on glycosaminoglycan (GAGs) and proteoglycan research, but the approach can be generalized. The methods described span the development of glycomics standards from CarbBank to Glyco Connection Tables. The existence of integrated data sets provides a foundation for novel methods of analysis such as machine learning for knowledge discovery. The implications of predictive analysis are examined in relation to disease biomarker to expand the target audience of GAG and proteoglycan research.

Characterization of glycosaminoglycan (GAG) sulfatases from the human gut symbiont Bacteroides thetaiotaomicron reveals the first GAG-specific bacterial endosulfatase

Despite the importance of the microbiota in human physiology, the molecular bases that govern the interactions between these commensal bacteria and their host remain poorly understood. We recently reported that sulfatases play a key role in the adaptation of a major human commensal bacterium, Bacteroides thetaiotaomicron, to its host (Benjdia, A., Martens, E. C., Gordon, J. I., and Berteau, O. (2011) J. Biol. Chem. 286, 25973-25982). We hypothesized that sulfatases are instrumental for this bacterium, and related Bacteroides species, to metabolize highly sulfated glycans (i.e. mucins and glycosaminoglycans (GAGs)) and to colonize the intestinal mucosal layer. Based on our previous study, we investigated 10 sulfatase genes induced in the presence of host glycans. Biochemical characterization of these potential sulfatases allowed the identification of GAG-specific sulfatases selective for the type of saccharide residue and the attachment position of the sulfate group. Although some GAG-specific bacterial sulfatase activities have been described in the literature, we report here for the first time the identity and the biochemical characterization of four GAG-specific sulfatases. Furthermore, contrary to the current paradigm, we discovered that B. thetaiotaomicron possesses an authentic GAG endosulfatase that is active at the polymer level. This type of sulfatase is the first one to be identified in a bacterium. Our study thus demonstrates that bacteria have evolved more sophisticated and diverse GAG sulfatases than anticipated and establishes how B. thetaiotaomicron, and other major human commensal bacteria, can metabolize and potentially tailor complex host glycans.

Harnessing glycomics technologies: integrating structure with function for glycan characterization

Glycans, or complex carbohydrates, are a ubiquitous class of biological molecule which impinge on a variety of physiological processes ranging from signal transduction to tissue development and microbial pathogenesis. In comparison to DNA and proteins, glycans present unique challenges to the study of their structure and function owing to their complex and heterogeneous structures and the dominant role played by multivalency in their sequence-specific biological interactions. Arising from these challenges, there is a need to integrate information from multiple complementary methods to decode structure-function relationships. Focusing on acidic glycans, we describe here key glycomics technologies for characterizing their structural attributes, including linkage, modifications, and topology, as well as for elucidating their role in biological processes. Two cases studies, one involving sialylated branched glycans and the other sulfated glycosaminoglycans, are used to highlight how integration of orthogonal information from diverse datasets enables rapid convergence of glycan characterization for development of robust structure-function relationships.

Heparin and heparan sulfate: analyzing structure and microheterogeneity

The structural microheterogeneity of heparin and heparan sulfate is one of the major reasons for the multifunctionality exhibited by this class of molecules. In a physiological context, these molecules primarily exert their effects extracellularly by mediating key processes of cellular cross-talk and signaling leading to the modulation of a number of different biological activities including development, cell proliferation, and inflammation. This structural diversity is biosynthetically imprinted in a nontemplate-driven manner and may also be dynamically remodeled as cellular function changes. Understanding the structural information encoded in these molecules forms the basis for attempting to understand the complex biology they mediate. This chapter provides an overview of the origin of the structural microheterogeneity observed in heparin and heparan sulfate, and the orthogonal analytical methodologies that are required to help decipher this information.

Low-molecular-weight heparins: differential characterization/physical characterization

Low-molecular-weight heparins (LMWHs), derived from unfractionated heparin (UFH) through different depolymerization processes, have advantages with respect to the parent heparin in terms of pharmacokinetics, convenience of administration, and reduced side effects. Each LMWH can be considered as an independent drug with its own activity profile, placing significance on their biophysical characterization, which will also enable a better understanding of their structure-function relationship. Several chemical and physical methods, some involving sample modification, are now available and are reviewed.

Hyphenated techniques for the analysis of heparin and heparan sulfate

The elucidation of the structure of glycosaminoglycan has proven to be challenging for analytical chemists. Molecules of glycosaminoglycan have a high negative charge and are polydisperse and microheterogeneous, thus requiring the application of multiple analytical techniques and methods. Heparin and heparan sulfate are the most structurally complex of the glycosaminoglycans and are widely distributed in nature. They play critical roles in physiological and pathophysiological processes through their interaction with heparin-binding proteins. Moreover, heparin and low-molecular weight heparin are currently used as pharmaceutical drugs to control blood coagulation. In 2008, the health crisis resulting from the contamination of pharmaceutical heparin led to considerable attention regarding their analysis and structural characterization. Modern analytical techniques, including high-performance liquid chromatography, capillary electrophoresis, mass spectrometry, and nuclear magnetic resonance spectroscopy, played critical roles in this effort. A successful combination of separation and spectral techniques will clearly provide a critical advantage in the future analysis of heparin and heparan sulfate. This review focuses on recent efforts to develop hyphenated techniques for the analysis of heparin and heparan sulfate.

Carbohydrate vaccines: developing sweet solutions to sticky situations?

Recent technological advances in glycobiology and glycochemistry are paving the way for a new era in carbohydrate vaccine design. This is enabling greater efficiency in the identification, synthesis and evaluation of unique glycan epitopes found on a plethora of pathogens and malignant cells. Here, we review the progress being made in addressing challenges posed by targeting the surface carbohydrates of bacteria, protozoa, helminths, viruses, fungi and cancer cells for vaccine purposes.

Heparan sulfate proteoglycans: structure, protein interactions and cell signaling

Heparan sulfate proteoglycans are ubiquitously found at the cell surface and extracellular matrix in all the animal species. This review will focus on the structural characteristics of the heparan sulfate proteoglycans related to protein interactions leading to cell signaling. The heparan sulfate chains due to their vast structural diversity are able to bind and interact with a wide variety of proteins, such as growth factors, chemokines, morphogens, extracellular matrix components, enzymes, among others. There is a specificity directing the interactions of heparan sulfates and target proteins, regarding both the fine structure of the polysaccharide chain as well precise protein motifs. Heparan sulfates play a role in cellular signaling either as receptor or co-receptor for different ligands, and the activation of downstream pathways is related to phosphorylation of different cytosolic proteins either directly or involving cytoskeleton interactions leading to gene regulation. The role of the heparan sulfate proteoglycans in cellular signaling and endocytic uptake pathways is also discussed.

A computational approach for deciphering the organization of glycosaminoglycans

BACKGROUND

Increasing evidence has revealed important roles for complex glycans as mediators of normal and pathological processes. Glycosaminoglycans are a class of glycans that bind and regulate the function of a wide array of proteins at the cell-extracellular matrix interface. The specific sequence and chemical organization of these polymers likely define function; however, identification of the structure-function relationships of glycosaminoglycans has been met with challenges associated with the unique level of complexity and the nontemplate-driven biosynthesis of these biopolymers.

METHODOLOGY/PRINCIPAL FINDINGS

To address these challenges, we have devised a computational approach to predict fine structure and patterns of domain organization of the specific glycosaminoglycan, heparan sulfate (HS). Using chemical composition data obtained after complete and partial digestion of mixtures of HS chains with specific degradative enzymes, the computational analysis produces populations of theoretical HS chains with structures that meet both biosynthesis and enzyme degradation rules. The model performs these operations through a modular format consisting of input/output sections and three routines called chainmaker, chainbreaker, and chainsorter. We applied this methodology to analyze HS preparations isolated from pulmonary fibroblasts and epithelial cells. Significant differences in the general organization of these two HS preparations were observed, with HS from epithelial cells having a greater frequency of highly sulfated domains. Epithelial HS also showed a higher density of specific HS domains that have been associated with inhibition of neutrophil elastase. Experimental analysis of elastase inhibition was consistent with the model predictions and demonstrated that HS from epithelial cells had greater inhibitory activity than HS from fibroblasts.

CONCLUSIONS/SIGNIFICANCE

This model establishes the conceptual framework for a new class of computational tools to use to assess patterns of domain organization within glycosaminoglycans. These tools will provide a means to consider high-level chain organization in deciphering the structure-function relationships of polysaccharides in biology.

Interactions between heparan sulfate and proteins-design and functional implications

Heparan sulfate (HS) proteoglycans at cell surfaces and in the extracellular matrix of most animal tissues are essential in development and homeostasis, and variously implicated in disease processes. Functions of HS polysaccharide chains depend on ionic interactions with a variety of proteins including growth factors and their receptors. Negatively charged sulfate and carboxylate groups are arranged in various types of domains, generated through strictly regulated biosynthetic reactions and with enormous potential for structural variability. The level of specificity of HS-protein interactions is assessed through binding experiments in vitro using saccharides of defined composition, signaling assays in cell culture, and targeted disruption of genes for biosynthetic enzymes followed by phenotype analysis. While some protein ligands appear to require strictly defined HS structure, others bind to variable saccharide domains without any apparent dependence on distinct saccharide sequence. These findings raise intriguing questions concerning the functional significance of regulation in HS biosynthesis.

Capillary electrophoresis of complex natural polysaccharides

Complex natural polysaccharides, glycosaminoglycans (GAGs), are a class of ubiquitous macromolecules that exhibit a wide range of biological functions and participate and regulate multiple cellular events and (patho)physiological processes. They are generally present either as free chains (hyaluronic acid and bacterial acidic polysaccharides) or as side chains of proteoglycans (PGs; chondroitin/dermatan sulfate, heparin/heparan sulfate, and keratan sulfate) and are most often found in cell membranes and in the extracellular matrix. The recent emergence of modern analytical tools for their study has produced a virtual explosion in the field of glycomics. CE, due to its high resolving power and sensitivity, has been useful in the analysis of intact GAGs and GAG-derived oligosaccharides and disaccharides affording concentration and structural characterization data essential for understanding the biological functions of GAGs. In this review, novel off-line and on-line CE-MS and MS/MS methods for screening of GAG-derived oligosaccharides and disaccharides will be discussed.

Proteoglycanomics: tools to unravel the biological function of glycosaminoglycans

Glycosylation is the most frequent PTM and contributes significantly to the function of proteins depending on the type of glycosylation. Especially glycan structures like the glycosaminoglycans are considered to constitute themselves the major function of the glycoconjugate which is therefore termed proteoglycan. Here we review recent views on and novel tools for analysing the proteoglycanome, which are directly related to the type of glycanation under investigation. We define the major function of the proteoglycanome to be its interaction with various proteins in many different (patho-)physiological conditions. This is exemplified by the differential glycosaminoglycan-interactome of healthy versus arthritic patient sera.

Characterization of di- and monosulfated, unsaturated heparin disaccharides with terminal N-sulfated 1,6-anhydro-β-d-glucosamine or N-sulfated 1,6-anhydro-β-d-mannosamine residues

Modified heparin disaccharides were obtained by the alkaline treatment of a solution containing the disulfated heparin disaccharide DeltaHexA-alpha-(1-->4)-D-GlcNSO(3),6SO(3). Their structures were characterized by one- and two-dimensional NMR spectroscopy: DeltaHexA-alpha-(1-->4)-1,6-anhydro-GlcNSO(3), DeltaHexA-alpha-(1-->4)-1,6-anhydro-ManNSO(3) and DeltaHexA-alpha-(1-->4)-ManNSO(3),6OSO(3). NMR spectroscopy, in combination with HPLC, provided the composition of the mixture. Characteristic NMR signals of the disaccharides were identified, even at low levels, in a high field of (1)H-(13)C correlation NMR spectra (HSQC) of a low molecular weight heparin (LMWH) obtained by beta-elimination (alkaline hydrolysis) of heparin benzyl ester, providing a more complete structural profile of this class of compounds.

Separation and analysis of nanomole quantities of heparin oligosaccharides using on-line capillary isotachophoresis coupled with NMR detection

Glycosaminoglycans (GAGs) are important in a number of biological processes and are structurally altered in many pathological conditions. The complete determination of GAG primary structures has been hampered by the lack of sensitive and specific analytical techniques. Nuclear magnetic resonance spectroscopy (NMR) is a powerful tool for GAG structure elucidation despite its relatively poor limits of detection. Solenoidal microcoils have greatly enhanced the mass limits of detection of NMR, enabling the on-line coupling of microseparation and concentration techniques such as capillary isotachophoresis (cITP), which can separate and concentrate analytes by 2-3 orders of magnitude. We have successfully used cITP coupled with on-line NMR detection to separate and concentrate nanomole quantities of heparin oligosaccharides. This sensitive on-line measurement approach has the potential to provide new insights into the relationships between biological function and GAG microstructures.

GLYCOMICS APPROACH TO STRUCTURE-FUNCTION RELATIONSHIPS OF GLYCOSAMINOGLYCANS

Extracellular modulation of phenotype is an emerging paradigm in this current postgenomics age of molecular and cell biology. Glycosaminoglycans (GAGs) are primary components of the cell surface and the cell-extracellular matrix (ECM) interface. Advances in the technology to analyze GAGs and in whole-organism genetics have led to a dramatic increase in the known important biological role of these complex polysaccharides. Owing to their ubiquitous distribution at the cell-ECM interface, GAGs interact with numerous proteins and modulate their activity, thus impinging on fundamental biological processes such as cell growth and development. Many recent reviews have captured important aspects of GAG structure and biosynthesis, GAG-protein interactions, and GAG biology. GAG research is currently at a stage where there is a need for an integrated systems or glycomics approach, which involves an integration of all of the above concepts to define their structure-function relationships. Focusing on heparin/heparan (HSGAGs) and chondroitin/dermatan sulfate (CSGAGs), this review highlights the important aspects of GAGs and summarizes these aspects in the context of taking a glycomics approach that integrates the different technologies to define structure-function relationships of GAGs.

Glycomics: an integrated systems approach to structure-function relationships of glycans

In comparison with genomics and proteomics, the advancement of glycomics has faced unique challenges in the pursuit of developing analytical and biochemical tools and biological readouts to investigate glycan structure-function relationships. Glycans are more diverse in terms of chemical structure and information density than are DNA and proteins. This diversity arises from glycans' complex nontemplate-based biosynthesis, which involves several enzymes and isoforms of these enzymes. Consequently, glycans are expressed as an 'ensemble' of structures that mediate function. Moreover, unlike protein-protein interactions, which can be generally viewed as 'digital' in regulating function, glycan-protein interactions impinge on biological functions in a more 'analog' fashion that can in turn 'fine-tune' a biological response. This fine-tuning by glycans is achieved through the graded affinity, avidity and multivalency of their interactions. Given the importance of glycomics, this review focuses on areas of technologies and the importance of developing a bioinformatics platform to integrate the diverse datasets generated using the different technologies to allow a systems approach to glycan structure-function relationships.

Chemical approaches to deciphering the glycosaminoglycan code

Glycosaminoglycans are sulfated biopolymers with rich chemical diversity and complex functions in vivo, contributing to processes ranging from cell growth and neuronal development to viral invasion and neurodegenerative disease. Recent studies suggest that glycosaminoglycans may encode information in the form of a 'sulfation code,' whereby discrete modifications to the polysaccharide backbone may direct the location or activities of proteins.

Complex glycosaminoglycans: profiling substitution patterns by two-dimensional nuclear magnetic resonance spectroscopy

Biological and pharmacological interactions of heparin and structurally related glycosaminoglycans (GAGs) such as heparan sulfate (HS) involve complex sequences of variously sulfated uronic acid and aminosugar residues. Due to their structural microheterogeneity, these sequences are usually characterized in statistical terms, by high-performance liquid chromatographic analysis of fragments obtained by enzymatic or chemical degradation. Nuclear magnetic resonance (NMR) spectroscopy is also currently used for structural characterization of GAGs. However, the use of monodimensional NMR analysis of complex GAGs is often limited by severe signal overlap that does not allow reliable quantitative measurements. Using magnetically equivalent signals, the higher resolution achieved by two-dimensional NMR methods could be also exploited for quantitative applications. In this work, heteronuclear single quantum coherence (HSQC) spectroscopy has been evaluated to determine variously substituted monosaccharide components of HS and HS mimics obtained by chemical modification of the Escherichia coli K5 polysaccharide (K5-PS) structurally related to the common biosynthetic precursor of heparin and HS. Heparin was used as a model for assessing the influence of 1H-13C spin-spin couplings on "volumes" of the corresponding signals. For major signals, the HSQC approach permitted quantification of additional structural features both in heparins and in a typical HS. The method was applied to profile the substitution patterns of K5-PS derivatives involving different degrees of N,O-sulfation and N-acetylation, including O-sulfated heparosans bearing free amino groups.

Glycomics: a pathway to a class of new and improved therapeutics

Complex glycans that are located at the surface of cells, deposited in the extracellular matrix and attached to soluble signalling molecules have a crucial role in the phenotypic expression of cellular genotypes. However, owing to their structural complexity and some redundancy in terms of structures that elicit a function, the therapeutic potential of complex glycans has not been well exploited, with a few notable exceptions. This review outlines recent advances that promise to increase our ability to use complex glycans as therapeutics. Opportunities for the development of further structure-function relationships for these complex molecules are also discussed.

Chromatographic analysis and sequencing approach of heparin oligosaccharides using cetyltrimethylammonium dynamically coated stationary phases

C(18) and C(8) bonded stationary phases dynamically coated with cetyltrimethylammonium (CTA) and strong anion exchange (SAX) were developed to obtain separations of oligosaccharide mixtures resulting from chemical or enzymatic depolymerization of heparin. With this method, the retention of sulfated oligosaccharides is directly adjustable depending on the amount of CTA adsorbed into the column. Oligosaccharides containing up to 20 sulfates were separated with a resolving power superior to that of conventional SAX analysis. The stability of the column coating enables hundreds of injections. Using ammonium methane sulfonate aqueous solutions as ultraviolet transparent mobile phases, it was possible to set up double detection, including selective detection of acetylated oligosaccharides. Analytical gel permeation chromatography was directly coupled to CTA-SAX, obtaining a two-dimensional profile of analyzed oligosaccharidic mixtures. A sequencing method of heparin oligosaccharides using partial depolymerization by heparinases according to their size and sulfation pattern and digest analysis by CTA-SAX was developed. A direct application of this method to the analysis of oligosaccharide mixtures obtained by complete digestion of heparins by heparinases I, II, and III was done. It allowed a reliable quantification of heparin building blocks. We also focused our attention on di- and tetrasaccharidic species containing the 3-O-sulfated glucosamines taken as markers of the active sites for antithrombin III. The method was also applied to more complex mixtures resulting from porcine heparin partially depolymerized with heparinase I. The specificity of the reaction was studied up to decasaccharidic fractions.